Establishment of asymptomatic bacteriuria is a novel alternative to antimicrobial therapy for management of recurrent bacterial urinary tract infection in humans and may also be useful for dogs if it can be shown that colonization of the canine bladder can be achieved. A three-dose protocol for Escherichia coli strain 83972 inoculation was developed to attempt induction of persistent bacteriuria in healthy dogs. A previous study using a single inoculation colonized dogs for no longer than 10 days and multi-dose protocols have been used to establish persistent bacteriuria in human patients. Three doses of approximately 10(9)E. coli 83972 bacteria were introduced into the bladder of eight healthy female dogs over 24h via an indwelling sterile urinary catheter. Three additional dogs were sham-inoculated. Duration of colonization ranged from 1 to 28 days (median 2 days) with no discernible reason for the prolonged colonization in one dog. Multi-dose inoculation of healthy dogs was not obviously superior to our previous use of single-dose inoculation apart from one dog remaining colonized for 28 days following the three-dose inoculation protocol.